New Landowner Etiquette

One time I had this little roadside lot I fixed it up, built a garden, a house,etc.
and sold the lot with next buyer able to have the objects. Property was sold no longer mine for months, then I got a message saying that my objects were on their land in this sim I hadn't been in months.
I was shocked but I had no problem removing the objects.
The person was new and didn't know they could return objects. Usually I think it is just easier if you return objects when you change your land settings when buying land.
You're under no obligation to keep other people's prims on your land or even allow them to build their unless you want them too when you buy the land.